(a) Field of the Invention
The present invention relates to an automatic accompaniment apparatus for use in or with an electronic musical instrument, and more particularly it pertains to an improvement of the performance control on the basis of chord type detection.
(b) Description of the Prior Art
In the past, there has been known an accompaniment apparatus for an electronic musical instrument which is so structured as to be operative that, based on the key depression signals supplied from the accompaniment keyboard (e.g. lower keyboard), a chord type such as major, minor and the like, and a root note are detected, and that, along therewith, based on the accompaniment pattern corresponding to the detected chord type and also on the detected root note, accompaniment tones such as chord tones, bass tones, etc. are generated (see, for example, Japanese Patent Preliminary Publication No. Sho 59-140495). And, in the automatic accompaniment apparatus of the above-mentioned type, it has been the usual practice to provide an automatic bass chord (ABC) mode selection switch so that, only when this selection switch is turned on, automatic accompaniment controlling via the accompaniment keyboard is made feasible.
According to the above-mentioned prior art, however, it should be noted that, in the state the ABC mode selection switch has been turned on, there arises such an inconvenience that, even when a melody, for example, is played on the accompaniment keyboard, there are produced only the specific chord tones or like tones (which tones are not stopped of their production even by release of the depressed keys) for the reasons that no chord has been established, and therefore, the player is no longer able to play a melody, hence the drawback that the expressions of performance are restricted.
Also, in case it is intended to generate musical tones as per the key depressions which the player performs on the accompaniment keyboard, there is in fact no other way for the user but to turn off the ABC mode selection switch (i.e. to release the ABC mode). Engaging oneself in such a switching operation in the midst of a musical performance has constituted a cause for hampering the smooth progression of the performance.
Not only that, in case the ABC mode is released, the automatic accompaniment becomes no longer utilizable, thus sacrificing the richness of performance.